// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PROCESS_PORT_PROVIDER_MAC_H_
#define BASE_PROCESS_PORT_PROVIDER_MAC_H_

#include <mach/mach.h>

#include "base/base_export.h"
#include "base/macros.h"
#include "base/observer_list.h"
#include "base/process/process_handle.h"
#include "base/synchronization/lock.h"

namespace base {

// Abstract base class that provides a mapping from ProcessHandle (pid_t) to the
// Mach task port. This replicates task_for_pid(), which requires root
// privileges.
class BASE_EXPORT PortProvider {
public:
    PortProvider();
    virtual ~PortProvider();

    class Observer {
    public:
        virtual ~Observer() {};
        // Called by the PortProvider to notify observers that the task port was
        // received for a given process.
        // No guarantees are made about the thread on which this notification will
        // be sent.
        // Observers must not call AddObserver() or RemoveObserver() in this
        // callback, as doing so will deadlock.
        virtual void OnReceivedTaskPort(ProcessHandle process) = 0;
    };

    // Returns the mach task port for |process| if possible, or else
    // |MACH_PORT_NULL|.
    virtual mach_port_t TaskForPid(ProcessHandle process) const = 0;

    // Observer interface.
    void AddObserver(Observer* observer);
    void RemoveObserver(Observer* observer);

protected:
    // Called by subclasses to send a notification to observers.
    void NotifyObservers(ProcessHandle process);

private:
    // ObserverList is not thread-safe, so |lock_| ensures consistency of
    // |observer_list_|.
    base::Lock lock_;
    base::ObserverList<Observer> observer_list_;

    DISALLOW_COPY_AND_ASSIGN(PortProvider);
};

} // namespace base

#endif // BASE_PROCESS_PORT_PROVIDER_MAC_H_
